Sentence Structure:

Remember that in order for a clause to be independent, it must have both a subject and a predicate.
Simple Sentences:
A
simple sentence has only one independent clause with no subordinating clauses.
A simple sentence may appear complicated because it can have compound subjects and predicates, prepositional phrases, appositives, verbal phrases, and adjectives that all make the sentence seem more complex; however, the sentence is still considered simple despite the sentence expansions.
:EXAMPLES:
Dogs howl. [simple sentence]
Dogs and coyotes howl. [simple sentence with a compound subject]
Dogs howl and yelp. [simple sentence with a compound predicate]
Dogs and coyotes howl and yelp. [simple sentence with compound subject and compound predicate]
Dogs and coyotes howl and yelp in the middle of the night. [simple sentence with a prepositional phrase]


Compound Sentences:
A
compound sentence** has two or more independent clauses and no subordinating clauses.
In a compound sentence, both clauses must have a subject and a predicate (aka independent clause).

The independent clauses in a compound sentence are usually joined by a comma and a coordinating conjunction (and, but, for, nor, so, yet, or for).
Independent clauses in a compound sentence can also be joined by a semicolon.

:EXAMPLES:

Cats meow, and dogs bark. [2 independent clauses]
Cats meow, and dogs bark, yet cows moo. [3 independent clauses]
The ferocious dog was foaming at the mouth; the cat fled his presence. [2 independent clauses joined by a semicolon]


Complex Sentences:
A Complex Sentence has one independent clause and one or more dependent clauses.
If the sentence begins with a dependent clause, then it is always followed by a comma.